Purification of ethers



United States Patent 3,458,410 PURlFICATION 0F ETHERS Evan A. Mayerle and Edward A. Hunter, Lake Jackson, Tex., assignors to Nalco Chemical Company, Chicago, Ill, a corporation of Delaware No Drawing. Filed July 30, 1965, Ser. No. 476,187

Int. Cl. B01k 3/00 US. Cl. 204-59 14 Claims ABSTRACT OF THE DISCLOSURE Ethers and particularly ethers used as solvents for Grignard reagents in electrolytes are purified by contacting them with sulfuryl chloride in sufiicient amount to reduce the concentration of the alcoholic impurities.

This invention relates to the purification of ethers and more particularly to the purification of ethers used as solvents for Grignard reagents in electrolytes which are electrolyzed, using a lead anode, to produce organic lead compounds.

In the manufacture of organic lead compounds by electrolyzing a solution of a Grignard reagent in an ether.- using a lead anode, various polyethers of glycols have heretofore been employed as solvents. When the electrolyte is processed in order to recover organic lead compounds therefrom, these ether solvents are sometimes decomposed to give alcoholic by-products of Which an appreciable fraction is preferentially soluble in the ether stream. The ethers containing these ether soluble impurities, if recycled back into the electrolyte, will react with the Grignard reagent and cause losses of magnesium and organic halides, thereby increasing the cost and reducing the efficiency of the process.

One of the objects of the present invention is to provide a new and improved process for removing active hydrogen compounds, such as alcoholic impurities, from organic polyethers without otherwise adversely affecting the utility of these ethers as solvents for Grignard reagents in electrolytes employed in an electrolytic system for making organic lead compounds, using a lead anode.

A further object of the invention is to provide a process for purifying organic ethers which can be employed not only in the recovery system for the removal of active hydrogen compounds, such as alcohols, prior to recycling the ether solvent, but also in the initial treatment of the solvent in order to remove such impurities when the electrolyte is first prepared, that is, when the organic polyether is first used to make a solvent solution of the Grlgnard reagent.

A more specific object of the invention is to provide a new and improved process for purifying organic polyethers used in electrolytes containing a Grignard reagent made by reacting magnesium and methyl chloride in an organic diether solvent.

Another specific object of the invention is to provide a new and improved process for purifying rather heavy or high boiling organic polyethers which boil at temperatures above 110 C.

A further specific object of the invention is to provide a new and improved process for purifying solvent mixtures which contain organic polyethers as well as other organic compounds, including, for example, hydrocarbons, and/or tetrahydrofuran. Other objects will appear hereinafter.

In accordance with the present invention it has been found that organic polyether solvents containing active hydrogen compounds, such as alcohols, can be purified by bringing them into contact with sulfuryl chloride (SO CI In order to evaluate the invention the impurity level of the organic polyether was measured by an activity test which was a modified Zerewitenoff test wherein a 10 ml. sample of the material to be tested was added to an excess of Grignard reagent and the volume of gas evolved was measured to determine the content of active hydrogen impurities (alcohols). By measuring the activity before and after treatment with sulfuryl chloride, it is possible to determine the percent reduction of active hydrogen impurities resulting from the sulfuryl chloride treatment.

The invention will be further illustrated but is not limited by the following examples in which the quantities are by weight unless otherwise indicated.

EXAMPLE I 897 grams of plant dried hexyl ethyl carbitol (containing about 20% diphenyl) was contacted With 4.5 grams SO CI at about C. The mixture was agitated and held at this temperature. At intervals, samples were pulled from the mixture, neutralized with Na CO solution, washed in water, and dried by blowing with nitrogen at 100 C. to C. The materials were then analyzed for active hydroxyl content by adding a 10 ml. sample to an excess of methyl magnesium chloride and measuring the mls. of gas evolved (activity):

In this test, the activity in terms of milliliters of gas per 10 ml. sample of the untreated hexyl ethyl Carbitol was 50. Treatment with 0.5% of sulfuryl chloride for one hour reduced the activity to about 30. An additional contact period up to 4 hours reduced the activity to about 25. Thus, 50% to 60% of the active hydrogen impurities were removed. The resultant product could then be recycled for use in preparing additional quantities of Grignard reagent without substantial losses of magnesium and or ganic halide.

EXAMPLE II 894 grams of plant dried hexyl ethyl ether of diethylene glycol (about 20% diphenyl) was contacted with agitation at 100 C. to 110 C. with 44 grams sulfuryl chloride. As in Example I, samples were pulled at intervals, neutralized, washed and dried. The dried samples were then analyzed for activity.

In this test, the quantity of sulfuryl chloride Was 5% by weight of the solvent. The solvent before the test had an activity of 48 which was reduced by treatment with the sulfuryl chloride to a value of about 20 in 1 hour. Thus, there was a removal of active hydrogen impurities of about 58%.

EXAMPLE III 905 grams plant dried hexylethyl ether of dieth lene glycol (about 20% diphenyl) was treated as in Example II with 19 grams sulfuryl chloride. The activity data Was determined on samples pulled at intervals during the treatment.

The initial activity of 42 was reduced to an equilibrium value of about 24 in 15 minutes or less.

EXAMPLE IV This example illustrates the use of various proportions of sulfuryl chloride and shows the results obtained at 3 various temperatures and at times of treatment in the purifying of a heavy ether which in this case was the hexyl ethyl ether of diethylene glycol.

The method of treatment and of determining activity was carried out as previously described with the results .4 in which R is methyl and/or ethyl, and X is chlorine. Thus, tetramethyl lead can be made by electrolyzing methyl magnesium chloride in an anhydrous ether solution, using a lead anode, and tetraethyl lead can be made by electrolyzing ethyl magnesium chloride in an anhyshown in the following table. drous ether solution, using a lead anode.

The method of treatment and of determining activity The invention is also useful in the manufacture of was carried out as previously described with the results mixed alkyl lead compounds, such as, triethylmethyl lead, shown in the following table. diethyldimethyl lead and ethyltrimethyl lead, usually in TABLE S 0 01 Impurity level of other Heavy other, Wt. percent Temp, Time, Percent grams grams 011 other 0. minutes Untreated Treated reduction 227 3. 34 1. 45 90 56 42 25 227- 10.0 4. 22 90 so 55 22 61 221 25. 1 10. o 35 15 53 23 57 227 50. 1 1s. 1 35 30 56 31 44 It will be seen from the table that a very substantial the form of mixtures with tetraethyl lead and tetramethyl purification was obtained by treatment with sulfuryl chlolead by using as the electrolyte mixtures of methyl magride under various conditions and in various proportions. nesium chloride and ethyl magnesium chloride in an In general, it is preferable to use at least 0.5% by ether. Specific examples of other Grignard reagents are weight of sulfuryl chloride based on the weight of the ethyl magnesium bromide, isopropyl magnesium chloride, organic polyether but smaller amounts can be used and isopropyl magnesium bromide, butyl magnesium chlostill obtain some degree of purification. Large amounts ride, butyl magnesium bromide, amyl magnesium bromide, up to about 25% by weight of sulfuryl chloride based amyl magnesium chloride, and higher alkyl homologues. upon the weight of the ether have been employed but the Similarly, the phenyl magnesium chloride, phenyl magimprovement in results does not appear to justify their nesium bromide or mixtures of phenyl and ethyl maguse. A preferred amount is within the range of 1% to 5%. nesium chloride, or mixtures of phenyl and ethyl mag- The temperatures employed in the treatment are subnesium bromide, or mixtures of phenyl and methyl magject to variation but are preferably within the range of nesium chloride, or mixtures of phenyl and methyl mag- 25 C. to 110 C. nesium bromide can be electrolyzed to produce other or- The time of treatment is also subject to variation but ganic lead compounds containing the phenyl radical or is preferably within the range of 10 to 60 minutes. Even 35 both the phenyl and ethyl radicals, or both the phenyl a few minutes contact time has an appreciable effect. and methyl radicals, or both the phenyl and other alkyl While the invention is generally applicable to the treatadi als n case a higher alkyl magnesium halide s s ment of organic polyethers containing active hydrogen stituted for the ethyl magnesium halide or the methyl compounds, such as alcohols, its use is particularly immagnesium halide. In a similar manner benzyl magnesium portant in the purification of polyethers of glycols having chloride in an organic ether can be employed as an electhe following general formulae: tro l yl jte. I 1

e e ectro yte can, and preferably does, contain an %8 8 g R excess of organic halide over that required to form the 1 2- 5 Grignard reagent. (3) R-OR -OR -0R OR Th th (4) e e er to be purified can also contain one or more hydrocarbons such as, for example, toluene, benzene,

Where t e radicals R and 5 are hydrocarbon fadhcals Xylene, and diphenyl. The amounts of these hydrocarbons and the l'edieals 1, 2 3 and 4 are alkylone radloals in the electrolyte solvents usually do not exceed 25% containing two to Six carbon atonls- Thus, one of the by weight of the total solvent. Other substances, such as ra als R 1 5 can he hexyl and the other y one tetrahydrofuran, can be present and do not interfere with can be hexyl and the other propyl or isopropyl; one can h ifi ti treatment be hexyl and the other y secondary butyl, isebutyl As indicated by the examples, it is desirable to wash tertiary y one can he hexyl and the other amyl the sulfuryl chloride treated ether material with water y both can be p y or one can benzyl and thereafter to dry it. Drying is especially important and the other y The radicals 1, 2 3 and 4 are where the purified material is to be used as a solvent for preferably ethylene but can be, for example, propylene, a G i reagent 1,2-propylene, butylene, amylene or hexylene. For use In making organic lead compounds by a process of the ln electrolytes of the type previously described, the radrtype described using an ether of the type described as a Gals R ahd R5 h h prefirahly be such that the Poly solvent for the Grignard reagent, one method of operaether glycols fi h at 20 tion is to pass the spent electrolyte containing the organic The term Gnghard reageht used hefelh rhfers 9 lead compound, or compounds, and the ether solvent with the Product Qhtalhed by reachhg aPPr X1mate1Y equl' or without other solvents such as hydrocarbons and tetramolar Proporhcmsg"f a compohhd hahhg the formula hydrofuran and excess organic halide and unreacted RXahd Mg accorhhg to the equahoh: Grignard reagent into a recovery system where the or- RX+Mg RMgX ganic lead compound, or compounds, is separated and in which R represents the organic radical X represents removed from the solvent system. Where lower boiling the halogen atom f the Grignard reagent, and Mg is solvents, such as, tetrahydrofuran, ar e present, these are the conventional symbol for magnesium. The radical R usually ,Separated by frachohal dfihhahoh or In some can be, f example methyl ethyl, propyl, isopropyl, other suitable manner. Lower boiling hydrocarbon solbutyl and higher homologues, phenyl, benzyl, and the vents, such as toluene, are usually allowed to remain with like. The radical X can be, for example, chlorine, bromine the organic load Product, especially Where the letter has r i din a boiling point close to that of toluene, as in the case of The invention is especially useful in purifying an ether tetramethyl lead. If higher boiling organic solvents, such solvent solution of a Grignard reagent which is elecas, diphenyl, are used in the process, these are usually trolyzed in the presence of a sacrificial lead anode and allowed to remain with the higher boiling ethers and the mixture of higher boiling ethers and higher boiling hydrocarbon solvents is recycled. During this recovery procedure acids or other neutralizing agents can be added in order to remove unreacted Grignard reagent, and excess organic halide, if volatile, can be removed by volatilization in a conventional gas stripping apparatus. Some of these procedures, expecially heating and acidizing, have a degrading effect on the ethers causing the formation of active hydrogen impurities, such as alcohols, which are undesirable because they react with the Grignard reagent in the manner previously explained. The present invention makes it possible to control this degradation of these ethers and the formation of active hydrogen impurities by the simple addition of a small amount of sulfuryl chloride which does not have any degrading effect in itself and does not interfere with the normal operation of the electrolytic process or the recovery system. This addition of sulfuryl chloride can be made intermittently or continuously to the recovered solvents after the removal of the organic lead compounds. The addition can also be made before the separation of all of the organic lead compounds, for example, by intermittently adding a small stream of sulfuryl chloride to the residue remaining after removal of most of the organic lead compounds from the spent electrolyte. However, addition of sulfuryl chloride to solvent streams containing substantial amounts of organic lead compounds should be avoided since sulfuryl chloride will destroy the organic lead compound with consequent economic loss.

The invention is hereby claimed as follows:

1. A process for purifying ethers containing alcoholic impurities which comprises contacting said ethers with sulfuryl chloride in an amount effective to reduce the concentration of the active hydrogen impurities.

2. A process as claimed in claim 1 in which the ether is mixed with a hydrocarbon.

3. A process as claimed in claim 1 in which the resultant product is Washed with water and dried.

4. A process as claimed in claim 1 in which the resultant product is neutralized, washed with water, and dried.

5. A process for removing alcoholic impurities present in polyethers of glycols having the following formulae:

Where R and R are hydrocarbon radicals, and the radicals R R R and R are alkylene radicals containing 2 to 6 carbon atoms which comprises contacting such polyethers containing such impurities with sulfuryl chloride in amounts effective to reduce the concentration of the active hydrogen impurities.

6. A process a claimed in claim 5 in which the resultant product is washed with water and dried.

7. A process as claimed in claim 2 in which the ether is mixed with a hydrocarbon.

8. A process for purifying the hexylethylether of diethylene glycol containing alcoholic impurities which comprises contacting it with a quantity of sulfuryl chloride effective to reduce the concentration of said impurities.

9. A process for purifying the benzylethylether of triethylene glycol containing alcoholic impurities which comprises contacting it with a quantity of sulfuryl chloride effective to reduce the concentration of said impurities.

10. A process as claimed in claim 9 in which said ether solvent after treatment with sulfuryl chloride and before recycling is washed with water and dried.

11. A process as claimed in claim 9 in which said ether solvent after treatment with sulfuryl chloride and before recycling is neutralized, washed with water and dried.

12. A process as claimed in claim 9 in which the recycled ether also contains up to 25% by weight of a hydrocarbon.

13. A process for purifying the diethylether of tetraethylene glycol containing alcoholic impurities which comprises contacting it with a quantity of sulfuryl chloride effective to reduce the concentration of said impurities.

14. In the electrolytic manufacture of organic lead compounds wherein an electrolyte comprising a solution of a Grignard reagent in an ether solvent is electrolyzed, using a lead anode, and the ether solvent is recovered in a recovery system and recycled for use in the preparation of additional quantities of electrolyte, the step which comprises treating said solvent prior to recycling with sulfuryl chloride in sufiicient amount to reduce the concentration of alcoholic impurities.

References Cited UNITED STATES PATENTS 2,817,686 12/1957 Cicero et a1. 260-613 3,118,825 1/1964 Linsk 20459 3,236,887 2/1966 Hooks et al. 204158 XR 3,296,314 1/1967 Burns et al 260-616 FOREIGN PATENTS 259,329 10/1926 Great Britain.

OTHER REFERENCES Kharasch et al.: J.A.C.S., vol. 61 (August 1939), pp. 2142-2150.

HOWARD S. WILLIAMS, Primary Examiner U.S. Cl. X.R. 260613, 615, 616

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,458 ,410 July 29 1969 Evan A. Mayerle et a1 It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below':

Column 3, lines 6 to 8, cancel "The method of treatment and of determining activity was carried out as previously described with the results shown in the following table.. Column 6, line 1, claim reference numeral "2" should read Signed and sealed this 21st day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, I R.

Attesting Officer Commissioner of Patents 

